A power converter is, for example, installed between a battery and a motor, controls power stored in the battery, and supplies the controlled power to the motor. A power converter loaded on a hybrid vehicle or an electric vehicle, i.e., a large number of sub units (e.g., power modules) which forms a power control unit (PCU) generates heat, and there is a possibility such that the performance decreases due to the adverse effect of generated heat, and thus a cooling mechanism is necessary. Various cooling technologies have been proposed (see, for example, JP 2016-067096 A).
A power converter disclosed in JP 2016-067096 A includes a cooler on a casing. This cooler includes a fluid inlet in which a cooling fluid is introduced, and a fluid outlet from which the cooling fluid is discharged. The cooling fluid is circulated via a plurality of connection paths respectively connected to the fluid inlet and the fluid outlet. The connection portion between the fluid inlet and the connection path, and the connection portion between the fluid outlet and the connection path are sealed by respective sealers.
Each sealer includes a first sealing member in a loop shape which prevents the cooling fluid from being leaked to the exterior from the connection portion, a second sealing member in a loop shape that surrounds the first sealing member, and a drain passage provided between the first sealing member and the second sealing member. This drain passage is formed in the casing. The cooling fluid trapped between the first sealing member and the second sealing member is discharged to the exterior of the casing from a drain discharging port via the drain passage. Formed in the sealing surface of the casing are a first groove in a loop shape in which the first sealing member can be fit, and a second groove in a loop shape in which the second sealing member can be fit.
Patent Literature Document 1: Japanese Patent Application Laid-Open Publication No. 2016-067096.
According to the sealing structure disclosed in JP 2016-067096 A, it is necessary to form both the first groove and the second groove in the sealing surface of the casing. The space between the first groove and the second groove is partitioned by a certain width. That is, a partition wall is provided between the first groove and the second groove. Since the diameter of the second groove increases by what corresponds to the partition wall, it is necessary for the sealing surface to have a large sealing space. Consequently, since the sealing surface becomes large, the casing and the cooler increase the respective sizes. This is disadvantageous to attempt downsizing of the power converter. In particular, when the complicated loop shape and the sealing members that are large respectively are employed, simply fitting each sealing member in each groove is disadvantageous in view of the assemble easiness, and thus there is a leeway for improvement.
An objective of the present disclosure is to provide a technology capable of improving the assemble easiness of a sealing member while achieving downsizing of a power converter.